build: integrate building ruby bindings into notmuch build process

Because ruby generates a Makefile, we have to use recursive make.
Because mkmf.rb hardcodes the name Makefile, put our Makefile{.local}
in the parent directory.

Makefile.local

@@ -59,7 +59,7 @@ endif
 FINAL_LIBNOTMUCH_LDFLAGS = $(LDFLAGS) $(AS_NEEDED_LDFLAGS) $(CONFIGURE_LDFLAGS)
 
 .PHONY: all
-all: notmuch notmuch-shared build-man
+all: notmuch notmuch-shared build-man ruby-bindings
 ifeq ($(MAKECMDGOALS),)
 ifeq ($(shell cat .first-build-message 2>/dev/null),)
 	@NOTMUCH_FIRST_BUILD=1 $(MAKE) --no-print-directory all

bindings/Makefile

@@ -0,0 +1,7 @@
+# See Makefile.local for the list of files to be compiled in this
+# directory.
+all:
+	$(MAKE) -C .. all
+
+.DEFAULT:
+	$(MAKE) -C .. $@

bindings/Makefile.local

@@ -0,0 +1,18 @@
+# -*- makefile -*-
+
+dir := bindings
+
+# force the shared library to be built
+ruby-bindings: lib/libnotmuch.so
+ifeq ($(HAVE_RUBY_DEV),1)
+	cd $(dir)/ruby && ruby extconf.rb --vendor
+	$(MAKE) -C $(dir)/ruby
+else
+	@echo Missing dependency, skipping ruby bindings
+endif
+
+CLEAN += $(patsubst %,$(dir)/ruby/%, \
+	.RUBYARCHDIR.time \
+	Makefile database.o directory.o filenames.o\
+	init.o message.o messages.o mkmf.log notmuch.so query.o \
+	status.o tags.o thread.o threads.o)

bindings/ruby/README

@@ -0,0 +1,7 @@
+To build the the notmuch ruby extension, run the following commands
+from the *top level* notmuch source directory:
+
+% ./configure
+% make ruby-bindings
+
+The generic documentation about building notmuch also applies.

configure

@@ -21,6 +21,7 @@ srcdir=$(dirname "$0")
 
 subdirs="util compat lib parse-time-string completion doc emacs"
 subdirs="${subdirs} performance-test test test/test-databases"
+subdirs="${subdirs} bindings"
 
 # For a non-srcdir configure invocation (such as ../configure), create
 # the directory structure and copy Makefiles.
@@ -474,6 +475,15 @@ else
     have_doxygen=0
 fi
 
+printf "Checking for ruby development files... "
+if ruby -e "require 'mkmf'"> /dev/null 2>&1; then
+    printf "Yes.\n"
+    have_ruby_dev=1
+else
+    printf "No (skipping ruby bindings)\n"
+    have_ruby_dev=0
+fi
+
 printf "Checking if sphinx is available and supports nroff output... "
 if command -v sphinx-build > /dev/null && ${python} -m sphinx.writers.manpage > /dev/null 2>&1 ; then
     printf "Yes.\n"
@@ -887,6 +897,10 @@ HAVE_CANONICALIZE_FILE_NAME = ${have_canonicalize_file_name}
 # build its own version)
 HAVE_GETLINE = ${have_getline}
 
+# Are the ruby development files (and ruby) available? If not skip
+# building/testing ruby bindings.
+HAVE_RUBY_DEV = ${have_ruby_dev}
+
 # Whether the strcasestr function is available (if not, then notmuch will
 # build its own version)
 HAVE_STRCASESTR = ${have_strcasestr}
@@ -999,6 +1013,10 @@ NOTMUCH_HAVE_MAN=$((have_sphinx))
 
 # Name of python interpreter
 NOTMUCH_PYTHON=${python}
+
+# Are the ruby development files (and ruby) available? If not skip
+# building/testing ruby bindings.
+NOTMUCH_HAVE_RUBY_DEV=${have_ruby_dev}
 EOF
 
 # Finally, after everything configured, inform the user how to continue.

debian/rules

@@ -19,7 +19,6 @@ override_dh_auto_build:
 	dh_auto_build -- V=1
 	dh_auto_build --sourcedirectory bindings/python
 	cd bindings/python && $(python3_all) setup.py build
-	cd bindings/ruby && ruby extconf.rb --vendor && make
 	$(MAKE) -C contrib/notmuch-mutt
 
 override_dh_auto_clean: